/*
 * Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 */
#ifndef _LINUX_BOOTMEM_H
#define _LINUX_BOOTMEM_H

// #include <linux/mmzone.h>
// #include <asm/dma.h>
#include "list.h"
#include "mmzone.h"
#include "cache.h"
/*
 *  simple boot-time physical memory area allocator.
 */

extern unsigned long max_low_pfn;
extern unsigned long min_low_pfn;

/*
 * highest page
 */
extern unsigned long max_pfn;

#ifdef CONFIG_CRASH_DUMP
extern unsigned long saved_max_pfn;
#endif

/*
 * node_bootmem_map is a map pointer - the bits represent all physical 
 * memory pages (including holes) on the node.
 */
/* 内存管理未初始化时用于管理内存的数据结构,
 * 未初始化时对内存管理的要求是简单而不是高效和通用.
 * 最先适配分配器(first-best)(自举内存分配器)用于启动阶段内存管理.
 * 内存不连续的系统可能需要多个bootmem分配器。如NUMA计算机
 * 所有bootmem分配器保存在全局变量bdata_list中,用init_bootmem_core初始化.
 * 在UMA系统上,只需一个 bootmem_t 实例,即 contig_bootmem_data 。它通过 bdata 成员与
 * contig_page_data 关联起来。
 */
typedef struct bootmem_data {
	/* 保存系统中第一个物理页的开始地址,大多数体系结构是0 */
	unsigned long node_boot_start;
	/* 可以直接管理的物理地址空间中最后一页的编号.换句话说,即 ZONE_NORMAL 的结束页. */
	unsigned long node_low_pfn;
	/* 指向存储分配位图的内存区的指针。在IA-32系统上,用于该用途的内
	 * 存区紧接着内核映像之后。对应的地址保存在 _end 变量中,该变量在链接期间自动地插入到
	 * 内核映像中。每个bit 0：未使用，1：使用
	 */
	void *node_bootmem_map;
	unsigned long last_offset;
	/* 上一次分配的页的编号。如果没有请求分配整个页,则 last_offset 用作该页内
	 * 部的偏移量。这使得 bootmem 分配器可以分配小于一整页的内存区 
	 */
	unsigned long last_pos;
	/* 指定位图中上一次成功分配内存的位置,新的分配将由此开始 */
	unsigned long last_success;	/* Previous allocation point.  To speed
					 * up searching */
	/* 链表元素,表头为 bdata_list*/
	struct list_head list;
} bootmem_data_t;

extern unsigned long bootmem_bootmap_pages(unsigned long);
extern unsigned long init_bootmem(unsigned long addr, unsigned long memend);
/* UMA系统上释放内存 */
extern void free_bootmem(unsigned long addr, unsigned long size);
extern void *__alloc_bootmem(unsigned long size,
			     unsigned long align,
			     unsigned long goal);
extern void *__alloc_bootmem_nopanic(unsigned long size,
				     unsigned long align,
				     unsigned long goal);
extern void *__alloc_bootmem_low(unsigned long size,
				 unsigned long align,
				 unsigned long goal);
extern void *__alloc_bootmem_low_node(pg_data_t *pgdat,
				      unsigned long size,
				      unsigned long align,
				      unsigned long goal);
extern void *__alloc_bootmem_core(struct bootmem_data *bdata,
				  unsigned long size,
				  unsigned long align,
				  unsigned long goal,
				  unsigned long limit);

#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
extern void reserve_bootmem(unsigned long addr, unsigned long size);
/* UMA系统上初始化内存管理前使用的分配内存函数,在 ZONE_NORMAL 内存域分配内存 */
#define alloc_bootmem(x) \
	__alloc_bootmem(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
/* UMA系统上初始化内存管理前使用的分配内存函数,在 ZONE_DMA 内存域分配内存 */
#define alloc_bootmem_low(x) \
	__alloc_bootmem_low(x, SMP_CACHE_BYTES, 0)
/* UMA系统上与 alloc_bootmem 相似,_pages指数据的对齐方式,名字暗示所需的内存长度是以页为单位 */
#define alloc_bootmem_pages(x) \
	__alloc_bootmem(x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS)) /* __pa 将内存地址转换为页号 */
/* UMA系统上与 alloc_bootmem_low 相似,_pages指数据的对齐方式,名字暗示所需的内存长度是以页为单位 */
#define alloc_bootmem_low_pages(x) \
	__alloc_bootmem_low(x, PAGE_SIZE, 0)
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */

/* UMA系统停用bootmem分配器 */
extern unsigned long free_all_bootmem(void);
/* NUMA系统停用bootmem分配器 */
extern unsigned long free_all_bootmem_node(pg_data_t *pgdat);
extern void *__alloc_bootmem_node(pg_data_t *pgdat,
				  unsigned long size,
				  unsigned long align,
				  unsigned long goal);
extern unsigned long init_bootmem_node(pg_data_t *pgdat,
				       unsigned long freepfn,
				       unsigned long startpfn,
				       unsigned long endpfn);
extern void reserve_bootmem_node(pg_data_t *pgdat,
				 unsigned long physaddr,
				 unsigned long size);
/* NUMA系统上释放内存 */
extern void free_bootmem_node(pg_data_t *pgdat,
			      unsigned long addr,
			      unsigned long size);

#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
/* NUMA系统上初始化内存管理前使用的分配内存函数,在 ZONE_NORMAL 内存域分配内存,比alloc_bootmem多一个参数,为内存分配节点 */
#define alloc_bootmem_node(pgdat, x) \
	__alloc_bootmem_node(pgdat, x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
/* NUMA系统上与 alloc_bootmem_node 相似,_pages指数据的对齐方式,名字暗示所需的内存长度是以页为单位 */
#define alloc_bootmem_pages_node(pgdat, x) \
	__alloc_bootmem_node(pgdat, x, PAGE_SIZE, __pa(MAX_DMA_ADDRESS))
/* NUMA系统上初始化内存管理前使用的分配内存函数,在 ZONE_DMA 内存域分配内存,_pages指数据的对齐方式,名字暗示所需的内存长度是以页为单位 */
#define alloc_bootmem_low_pages_node(pgdat, x) \
	__alloc_bootmem_low_node(pgdat, x, PAGE_SIZE, 0)
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */

#ifdef CONFIG_HAVE_ARCH_ALLOC_REMAP
extern void *alloc_remap(int nid, unsigned long size);
#else
static inline void *alloc_remap(int nid, unsigned long size)
{
	return NULL;
}
#endif /* CONFIG_HAVE_ARCH_ALLOC_REMAP */

// extern unsigned long __meminitdata nr_kernel_pages;
// extern unsigned long __meminitdata nr_all_pages;

extern void *alloc_large_system_hash(const char *tablename,
				     unsigned long bucketsize,
				     unsigned long numentries,
				     int scale,
				     int flags,
				     unsigned int *_hash_shift,
				     unsigned int *_hash_mask,
				     unsigned long limit);

#define HASH_EARLY	0x00000001	/* Allocating during early boot? */

/* Only NUMA needs hash distribution.
 * IA64 and x86_64 have sufficient vmalloc space.
 */
#if defined(CONFIG_NUMA) && (defined(CONFIG_IA64) || defined(CONFIG_X86_64))
#define HASHDIST_DEFAULT 1
#else
#define HASHDIST_DEFAULT 0
#endif
extern int hashdist;		/* Distribute hashes across NUMA nodes? */


#endif /* _LINUX_BOOTMEM_H */
